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Background: seeking modern technologies, resources, etc that could potentially be discovered and applied in a fantasy setting where manufacturing processes, while advanced, are more akin to the late 1700's. Society has access to "knowledge-base" of advanced species, but A) have currently only been able to interpret/apply portions of it and, B) lacks modern manufacturing technology.

My dilemma is composite materials, specifically alternatives to liquid-crystal polymers to be utilized in the production of advanced bowstrings and other materials. I know liquid-crystals are naturally occurring but am unclear if there is any means by which the polymer can be manufactured without leveraging advanced manufacturing processes or needing a natural source (cellulose, spider silk, etc).

Examples: dacron fiber, carbon fiber bows, advanced rubbers/resins, etc.

  • Open to imaginary materials, so long as we don't veer into the "unobtainium" spectrum
  • Assume hydraulics/pneumatics exist

To clarify: how/would a near-industrial civilization be capable of manufacturing materials comparative to dacron, kevlar, etc?

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  • $\begingroup$ What specific polymer do you want? Some semi-synthetic fibers, such as viscose (a.k.a. rayon, a.k.a. artificial sylk) were developed quite early, at the end of the 19th century; and, of course, nature is full of polymers. And why wouldn't those people use cellulose, which is, well, abundant? (They do have paper, don't they? Paper is made of cellulose.) $\endgroup$
    – AlexP
    May 25 at 8:19
  • $\begingroup$ I'm voting to close for now. We're expecting a question that has a 'best answer. Currently the question requests a list of materials. $\endgroup$
    – Trioxidane
    May 25 at 8:24
  • $\begingroup$ Updated. I'm specifically referring to advanced liquid-crystal polymers used in the development of dacron, kevlar, carbon fiber, etc. $\endgroup$
    – merz1v
    May 25 at 9:13
  • $\begingroup$ @AlexP there is paper, and I figured a special type of wood could be implemented for use as a replacement for composite materials (ironwood?) but wouldn't apply to things like hi-tensile fiber like that used in bowstrings, slingshots, tires, etc. $\endgroup$
    – merz1v
    May 25 at 9:20
  • $\begingroup$ Linen did everything needed for bowstrings until aramid ("Kevlar") was invented. Cellulose is a natural polymer. $\endgroup$
    – Zeiss Ikon
    May 25 at 15:30

4 Answers 4

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Why you can't make Kevlar without modern equipment.

The manufacture of Kevlar has a few roadblocks. Kevlar is made from p-Phenylenediamine and Terephthaloyl Chloride.

The p-Phenylenediamine part would be hard but doable. You need Aluminum Chloride as part of the production chain. The production of Aluminum Chloride typically requires electrolysis to isolate the aluminum using the most cost efficient method... that said, there are expensive, not electrolysis methods that you could use to get around this. All the other materials and processes used to make p-Phenylenediamine were available by the late 1700s.

The Terephthaloyl Chloride is the much harder part because you need to run naphtha through the catalytic reforming process to get to p-Xylene. This step requires complex and expensive refining equipment, and there is no simple substitute for this step that I can find. p-Xylene is needed at multiple steps in the production of Terephthaloyl Chloride.

This said, Kevlar might make good body armor, against bullets, but it does not have the best puncture resistance (which is what you actually need on a pre-modern battlefield). While it might outperform a linen based gambison, it will not protect you better that steel mail or plate armor would against most threats you will face. It is also not a good materials to use in bow construction because it is too stretchy and does not have a lot of snap back like certain other materials.

The modern synthetic materials you really want to replace are resin-fiberglass composites and nylon.

Natural Resin-fiberglass composites

The main reason modern bows shoot faster is because they are reinforced with fiberglass. Fiberglass springs back from deformation much faster than and wood or metal allowing a fiberglass backed bow arm to shoot nearly twice as fast as traditional bow of similar design.

This said, man-made resins and fiber glasses have naturally occurring counterparts. Asbestos is a naturally occurring fiberglass that people have been using for over 6000 years. In fact, it has a higher tensile strength than most man-made fiber glasses; so, as long as you don't mind occasionally needed to replace some dead bowyers due to its toxicity, it is a great material to use for this.

As for resins, there are many naturally occurring options made from various tree saps to pick from. Though you will specifically want to be looking at one of many possible "copal resin" trees. These trees have saps that when boiled, produce a hard amber like plastic very similar to the resins used in fiberglass composites today. While copal resins will not harden as quickly as modern epoxy resins, they can be very tough once set, and have also been in use for thousands of years.

That said, resin-fiberglass composites are good for more than just bows. Resin-fiberglass can also be used to improve the construction of ships, wagons, body armor, and tool handles just to name a few.

Natural Composite to Substitute for Nylon

As for the bowstring itself, the most important quality of a good bow string is that it does not stretch under tension. Modern bow strings are typically made from Nylon (Not Kevlar) specifically because Nylon can take significant load without stretching compared to other synthetic fibers.

Nylon is much easier to make than Kevlar too, and there are so many different variants of it, that there are a few that can be made without any complex equipment. That said, the ancient world already had a super material that may have been at least as good.

Like Nylon, cords made from horse or human hair are highly resistant to streching under load. Some of history's best bow cording material was invented by the Romans using a combination of animal sinew and human or horse hair reverse twisted together and reinforced with hide glue. Not only was this composite cording very comparable to the nylon bow strings we use today, but it does not require any complex chemistry to make.

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    $\begingroup$ Are you trying to say that we can make a superior material out of asbestos and natural sap? $\endgroup$
    – Alexander
    May 25 at 20:43
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    $\begingroup$ @Alexander It has to be the right kind of tree sap, but yes. Basically, you want to use a tree that is classified as a copal resin tree. cameo.mfa.org/wiki/Copal $\endgroup$
    – Nosajimiki
    May 25 at 21:36
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If I remember correctly, the Greeks had developed something akin to composites with linothorax: they would wrap linen bandages in a special way and it would become a lightweight and well performing armor.

Similarly the Japanese had an armor made of folded paper, which was pretty effective against swords and arrows.

It's not unconceivable that something similar can be done by you people.

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    $\begingroup$ (1) That would be linothorax, with an iota not a y and with -no-. The first part of the word is most likely cognate with English linen and German Lein, Leinen. (2) It's pre-classical and classical Greece, more than a thousand years before the days of the empire which called itself Roman and which is called Byzantine by modern historians. $\endgroup$
    – AlexP
    May 25 at 13:15
  • $\begingroup$ @AlexP editing the typo (and maybe adding the link) would have costed less time than typing another grumpy sounding comment. I keep wondering why. $\endgroup$
    – L.Dutch
    May 25 at 20:33
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    $\begingroup$ FYI, linothorax was not so much a matter of how it was wrapped, but how it was held together. Many historians believe it was made of layers of linen laminated with hide glue. The result was a material very similar to hardened leather. Hide glue is not as tough as resin, and linen is not as tough as fiberglass, but in principle at least, it was a precursor resin-fiberglass composites. $\endgroup$
    – Nosajimiki
    May 26 at 13:54
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Bugtech

Silk is the best known of these.

Another sweet insect derived biopolymer is shellac. https://en.wikipedia.org/wiki/Shellac

Shellac is scraped from the bark of the trees where the female lac bug, Kerria lacca (order Hemiptera, family Kerriidae, also known as Laccifer lacca), secretes it to form a tunnel-like tube as it traverses the branches of the tree. Though these tunnels are sometimes referred to as "cocoons", they are not cocoons in the entomological sense. This insect is in the same superfamily as the insect from which cochineal is obtained.

The raw shellac, which contains bark shavings and lac bugs removed during scraping, is placed in canvas tubes (much like long socks) and heated over a fire. This causes the shellac to liquefy, and it seeps out of the canvas, leaving the bark and bugs behind. The thick, sticky shellac is then dried into a flat sheet and broken into flakes, or dried into "buttons" (pucks/cakes), then bagged and sold. The end-user then crushes it into a fine powder and mixes it with ethyl alcohol before use, to dissolve the flakes and make liquid shellac.[10]

Shellac naturally dries to a high-gloss sheen.

Properties

...Shellac is a natural bioadhesive polymer and is chemically similar to synthetic polymers.[14] It can thus can be considered a natural form of plastic.

...History The earliest written evidence of shellac goes back 3,000 years, but shellac is known to have been used earlier.[6] According to the ancient Indian epic poem, the Mahabharata, an entire palace was built out of dried shellac.[6]

I am not sure about strings and filaments but there was definitely shellacked armor.

Silk bowstring is not too wild. Or you could invent polymers extracted and spun from a bug or bug casing like the lac bug, or some different organism along the lines of Tyrian purple extracted from snails.

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    $\begingroup$ Silk makes a decent Kevlar substitute for armor, but is not good for bow making. While its ultimate tensile strength is very high, it has a lot of stretch which is bad for making bow strings, and not much spring which makes it bad as a bow backing material. $\endgroup$
    – Nosajimiki
    May 26 at 15:41
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As far as I'm aware most of the 1700 was first subtracting stuff and then combining stuff to get what you want. Rather than have people create the base components I would let nature create it for you.

In many ways some spider silks can surpass Kevlar for example. The problem is that spiders are mostly solitary hunters that are hard to farm. But there are other bugs that produce silks, and in a fantasy setting you can justify natural pressures to come up with similar spidersilk properties.

  • a spidersilk worm. Just like the silkworm but adapted to a harsher environment where just that much more protection is needed, either to anchor the cocoon down or to protect against (bug) predators.
  • spidersilk ants. The weaver ant uses the larvae's ability to create cocoon silks to construct ant hives from leaves in the trees. An adaptation could see stronger silks created and subsequently farmed from them.

Graphene and especially Carbon Nanotubes are a tough but flexible material that have good properties in materials they are captured in. Damascus steel for example has it. I had a discussion with someone and we found a variety of different articles which indicated that almost every part of the process to create Graphene can be done by a biological being (bacteria mostly). If a creature used this in things like a shell, bone or tendons to strengthen themselves and these people farm these creatures in order to extract the CNT's and use it in something else, they could create strong composite materials without even knowing what a composite material is. You can also have a type of sapling create CNT's and be an excellent (if tough to cut down) material for bows.

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